Spring has come, but the economy refuses to blossom. With the days long and the cash short, now's the perfect time to get that dusty old bike out of your storage unit. After a little TLC you'll have a virtually free form of transport - with the added benefit of a little extra space in the unit in case you have to move in there yourself when times get really tough. And even if your steed is of relatively recent vintage or was never put away, it could probably use a little attention to bring it up to speed for the nice weather ahead.

Safety first

Your initial concern is the overall security and ride-ability of your bike, especially considering the local hills and traffic it will face. "This being San Francisco," says Paul Bray, head mechanic at the Presidio Sports Basement, "you want to check the brakes." A thorough brake test should be done while the bike is mounted, to ensure the brakes actually stop it. If the response is lacking, the brake pads likely need replacement. On older bikes, the rubber may have hardened over time. But even with a newer bike, hilly commutes in the rain - when water and grit act like a wet sander - can wear through a set of pads in a matter of months.

Check that the bolts securing the stem and handlebars are tight, and that the quick-release skewers on the wheels are properly installed. If you're not sure, ask a mechanic or one of your more experienced cycling friends.

Now air up the tires; even in good condition they lose up to 5 psi a week. Inspect the sidewalls for cracks. Some may just be surface blemishes, but if any are near the bead, where the tire enters the rim of the wheel, it should be replaced because the bead could separate under pressure. If the rear tire has lost much of its tread down the middle, or if there is a pronounced flat spot along its profile or if any of the inner threads are showing through, consider replacing it as well.

Gear up

Oil the chain and then remove as much lube as you can. "The biggest mistake people make is not taking a rag and wiping away the excess," Bray says, resulting in the build-up of "nasty junk that will just end up on your leg." You might want to have a shop check the chain for stretch as well, and replace it if necessary. In fact, now is a good time to install any new drive-train components, when they won't immediately be thrashed by soggy riding.

But first clean the gunk out from between the rear cogs you already have. Then shift through the gears to make sure they all engage. If there's a lag, try shifting the chain onto your largest cog, next to the wheel, then without turning the pedals, push the shift lever all the way back out to give you some slack in the cable. This will allow you to remove the housing from the rear of the cable, which you can now clean and oil.

Comfort and joy

Maybe your bike has been sitting idle because it fits badly or the drop bars are no longer comfortable. On most bikes from the early '90s or before, it's fairly easy to raise the handlebars a bit, and if your model has its shift levers on the frame rather than up with the brakes, you can install flat or riser bars without spending a fortune. Bigger, gel-filled saddles are also easy to come by, and retrofitting easier gears can make the hills less onerous. Luxuriate!

If you've been rocking fenders for the winter, consider taking them off - for lighter weight, to fit bigger tires or merely as a declaration that summer is nigh. Or leave them on, as spring showers may still crop up, and the mysterious puddles that appear on Market Street many weeks after the last hint of precipitation are the ones you really don't want splashing up on you.

It shouldn't cost more than $100 to get back on the road, and you probably wouldn't want to throw much more than $150 at an old 10-speed, since you can likely find a newer, better-working bike for that sum. And finally, this process is best initiated at least a day before your first ride so you'll know if you have issues beforehand, says Bray, "rather than finding that out halfway through the Headlands."

Bike About Town is presented by the San Francisco Bicycle Coalition, a 10,000-member nonprofit dedicated to creating safer streets and more livable communities by promoting the bicycle for everyday transportation. For more biking resources, go to www.sfbike.org.